1. Field
Embodiments described herein generally relate to reducing the formation of coke. More particularly, such embodiments relate to reducing the formation of coke in a fluid catalytic cracking unit.
2. Description of the Related Art
High residence time combined with high temperature foments coke formation in fluid catalytic cracking product mixtures produced in fluid catalytic cracking (“FCC”) units or processes. High residence time (low velocity) pockets of vapor in the FCC units give rise to the coke formation. The coke build up increases the risk that large chunks or pieces of the coke fall into and plug portions of the FCC unit potentially resulting in unit shutdown.
One approach for reducing the formation of coke has involved the introduction of coke suppressive additives to various locations within the FCC unit, e.g. transfer lines, risers, and/or reactor domes. These coke suppressive additives, however, increase operating cost and can have limited effectiveness, depending on the type of hydrocarbon feed introduced to the FCC unit and the particular products produced therein.
There is a continuing need, therefore, for better apparatus, systems, and methods for reducing the formation of coke in an FCC unit.